1. Field of the Invention
This invention relates generally to flexible shaft couplings having intermeshing teeth and more particularly to flexible gear couplings having means for permanently sealing a lubricant within the coupling for lubricating the intermeshing gear teeth.
2. Description of the Prior Art
Flexible gear couplings have been widely accepted in industry as a successful means for transmitting torque from a driving shaft to a substantially coaxially aligned driven shaft, particularly where high torque is to be transmitted between shafts that are radially and angularly misaligned. The construction and operation of such flexible gear couplings may be easily understood by reference to Fast U.S. Pat. No. 1,356,860 although many improvements have since been made to the basic design.
Since a typical gear coupling has meshing gear teeth, it is essential that the gear teeth be well lubricated at all times to prevent wear of the teeth. Lubrication of gear couplings has been a problem from their inception. Since gear couplings are used in a variety of applications, they are frequently removed from one pair of shafts and installed on other shafts or they may be stored in inventory for future use.
Typical gear couplings include two coupling halves bolted together to form a complete coupling although a single coupling half may be bolted to a flange on one of the shafts. One-half coupling is installed on each of the coaxially aligned shafts and the sleeves are bolted together to form a full coupling. When the half couplings are being installed, their ends are open and it is difficult to keep lubricant within the coupling, such lubricant usually being in liquid form although it may be a heavy grease. Many mechanics fail to replenish the lost lubricant. In addition, dirt, and grime may become mixed with the lubricant and damage the gear teeth causing premature failure of the coupling.
Another problem is that the lubricant must be of a special type to hold together and perform properly under the centrifugal forces inherent in a rotating coupling. There are very few lubricants that can be used in gear couplings. However, when the lubricant must be replenished, many mechanics use any lubricant that is available which may not maintain proper lubrication of the teeth.
In addition, it has been found that where the sleeves are connected a gasket must be used between the flanges to prevent leakage of the lubricant through the connection. However, under high centrifugal forces and temperatures the gasket may become weak, allowing the lubricant to seep between the flanges and out of the coupling.
Another problem with typical gear couplings is that the lubricant does not flow easily from one side of the meshing gear teeth to the other since it must flow through the spaces between the teeth. The spaces are very small and lubricant does not always reach all areas of the teeth if the lubricant remains on one side of the teeth.
Accordingly, an object of the invention is to provide a permanently sealed gear coupling that does not require periodic replacement of the lubricant. A further object is to provide means for applying lubricant to both sides of the gear teeth to enhance lubrication.